1. Field of the Invention
The invention relates to a technology that delivers a control program that controls an on-vehicle apparatus for installation in a vehicle.
2. Description of the Background Art
On a controller for installation in a vehicle, such as an engine controller or a navigation apparatus, various functions relevant to vehicle control are implemented by executing control programs. Such a control program for the controller requires reprogramming (updating of a program) for adding a new function or repairing a found fault. Proposed is the technology that updates such a control program of the controller through a network. For example, Japanese Patent Application Laid-open Publication No. 2010-243339 discloses a technology that updates a control program of a navigation apparatus through a network. The technology updates the control program while a vehicle is parked at home or the other place in order to prevent inadvertent update of the control program on the running vehicle.
However, it is assumed that, by the technology disclosed on the publication, the control program to be updated will grow in program size due to the complex functions, and that accordingly updating the program will take a longer time. Updating the program for a longer time increases the possibility that a user of the vehicle operates the devices installed in a vehicle.
Operation on the on-vehicle device by the user of the vehicle during updating of the control program causes fluctuation in voltage supplied by a battery of the vehicle. As a result, an operation of the apparatus whose control program is being updated fluctuates, which can lead to unsuccessful completion of updating the control program.